The title says it all - I have been unable to apply any pie goodness on any pseudo element.
All those selectors seem to be ignored completely, as I don't get any error and I am pretty clueless as to what might be wrong.
I have prepared a jsfiddle with a test case as I cannot push the file on my pie fork at the moment: http://jsfiddle.net/Razor/bgVbq/ (goes without saying that it needs to be copied in the /tests folder to see what's wrong)
Tests were done on IE8, with pie built from commit ebdc675
Couldn't try on IE9 and IE6/7 don't support these pseudo elements.
Let me know if I can help at all.
Unfortunately this is a limitation of IE itself -- it does not apply behaviors to generated content. Even if it did, it might be impossible to make PIE work on the generated content "elements", as they have no DOM of their own.
Thanks for the explanation - don't think there is a way to handle this from PIE, unless parsing the css directly and looking for rules with :before/:after containing the behaviour.